Again, I'm not saying this is good. Compared to the brevity of TeX or troff, it's difficult to accept. But XML is easier to read when you give in to its heavyweight structure and format it appropriately.
By the way, on my system (OSX, Chrome), the unicode version is beautiful. I had not realized it was a good math option.
The big downside with the Unicode option is the poor handling of fractions. It's not so apparent with the Quadratic Equation, but if your have a complex divisor the / notation starts to fall apart.
Even properly formatted that MathML version is just awful. You could help it a bit by combining some of those <mi> elements on a single line maybe, but it's way too much mental effort to parse that mess.
Lack of proper subscript and superscript support is a killer for Unicode as well. Unicode is amazing for smaller, simple equations, but anything beyond that soon becomes extremely hard to process.
By the way, on my system (OSX, Chrome), the unicode version is beautiful. I had not realized it was a good math option.